The invention applies more specifically, but not exclusively, to elements comprising tension members, such as metal strands of cables which, made up of a multiplicity of strands, are used in civil engineering and building activities.
Numerous structures and notably bridges comprise cables which are used in particular to support elements of these structures. Such cables are stressed in traction between their opposite ends by use of anchoring devices, which are used for fixing a structural cable to a building element. Frequently saddles, also known as guiding devices, are used for holding cables in such a manner as to deviate them in whatever way in the direction in which they must extend.
The function of a saddle of the type cited above is thus to permit lateral and/or longitudinal and local holding of a cable and transfer of the stress caused by this deviation to a support, such as a bridge pylon, provided for this purpose. A saddle of the aforementioned type is intended to be interposed between the support and the cable such as inside a pylon for stay cables or a bridge girder diaphragm for external tendons. Conventional saddles used one simple steel pipe for all strands, i.e. the bundle of strands placed inside one common pipe. In some solutions individual steel tubes were provided for the strands. More recently, saddles with holes or channels (obtained by so-called void formers which are removed after the grouting) for each individual strand were developed. In some solutions these holes have a V shape to improve the clamping effect. Saddles with individual tubes or channels are conceived to allow individual local support of each strand of a cable.
To this end, a recent saddle comprises at least one bearing area for guiding a strand of a cable, and preferably a plurality of bearing areas for deviation, each permitting the individual support of one of the strands of a cable.
Inside bridge anchoring devices and bridge saddles, the strands are often unsheathed to increase friction between the strands and some parts of the saddle or the anchoring device or to permit anchorage by wedging in the anchoring device. The increased friction helps to keep the strands in place in the anchoring device or in the saddle. However, the unsheathed strands are prone to corrosion, and for this reason the saddles and the anchoring devices need to be properly sealed off from the outside environment. In the context of this patent application, the term corrosion is used to mean any process, for example chemical or electrolytic, which can have a deleterious effect on the chemical integrity, and hence the mechanical properties, of the strands.
Another issue that needs to be taken into account is the fact that bridge structural cables, such as stay cables, are often exposed to strong winds. The exposure to wind creates forces on, and movements of, cables that are transferred to the rest of the structure. The problem is thus how to cope with cable deviation due to transverse load at the entrance of the saddle or anchoring device, and how to overcome cyclic loading due to vibrations which may damage the cable or the structure.
It is the aim of the present invention to provide an improved sealing arrangement to be used in bridge saddles and/or anchoring devices so that the shortcomings of the prior art can be overcome.